It is well known that the physical size of radio communications devices such as pagers and cellular telephones continues to decrease. Some recently introduced pagers are only slightly thicker than commonly available credit cards, an achievement attributable in part to the recent advent of so called surface-mount manufacturing technology.
Further reductions in the physical size and specifically the height of such communications devices will be limited by the height of the components that they are comprised of. In particular, if these radio communications devices are to be of conventional circuit designs, employing for example local oscillators that use quartz crystal devices for frequency control, the crystal packages will have to be substantially reduced in their thickness.
A problem with mounting small quartz crystals in thin packages is the maintenance of a clearance between the vibrating piezoelectric element and its housing. The piezo or quartz crystal element must include metallized electrodes and be compliantly mounted in such a way that the piezoelectric element can vibrate without being mechanically shocked or having its vibration damped by a mounting structure.
Various prior art mounting schemes for piezoelectric devices include the use of various resilient materials and bent or folded metallic tabs that cushion the piezoelectric device from shock and provide some conductive path between external circuitry for the device and the electrodes on the piezoelectric devices surfaces. A problem with these prior art mounting structures is their inability to maintain extremely close clearances, on the order of 0.005" or less between the surfaces of the piezoelectric device and its housing. In such a small housing, it is indeed often impossible to compliantly mount a very small quartz device using these prior art mounting structures in such a way that there is no risk that the vibrating quarts element will come in contact with its surroundings.
A quartz crystal package that provides an ultra thin external height dimension of 0.050 inches or less in thickness that compliantly mounts a piezoelectric element within an even smaller cavity would be an improvement over the prior art.